Air pumps

ABSTRACT

Air pumps are provided having channels therein to allow cool air to circulate throughout the interior of the pump to promote efficient and effective cooling of the pump. Additionally, a dampening or muffling arrangement is provided which substantially reduces the air borne operational noise of the pumps.

[ air. 21, 1972 2,042,510 6/1936 Corneliusetal..................

[54] AIR PUMPS [72] Inventors:

...417/413 X Small.....................................4l7/480 RobertRaymond Greene, Chicago; Hans Oscar Jacob, Morton Grove; Meredith WayneMeece, Niles, all of 111.

Primary ExaminerRobert M. Walker Assignee! International Telephone andTelegraph Att0rneyC. Cornell Remsen, Jr., Walter J. Baum, Percy P.

Corporation, New York, NY.

Jan. 21, 1970 21 Appl. No: 4,615

Lantzy, J. Warren Whitese], Delbert P. Warner and James B. Raden [22]Filed:

ABSTRACT A 'ddh' h lth'lll 1 s2U.S.Cl.....................,.........4l7/368,417/3l2,417/413,"pumpsarepmv'e avmgc mes mm air to circulate throughout the interior ofthe pump to 417/479, 417/480 .F04b 17/00, F04b 35/00, F04b 39/02,

promote efficient and effective cooling of the pump. Addi- F04) 21/00,F04) 45/00 tionally, a dampening or mufflmg arrangement 15 provided417/368 413 415 479 480 which substantially reduces the air borneoperational noise of the pumps.

[58] Field ofSearch..................

4 Claims, 6-Draw1ng Figures References Cited UNITED STATES PATENTS1,187,031 6/1916 Blacketal.........................417/415X PatentedMarch 21, 1972 5 Sheets-Sheet l Patented March 21, 1972 3,650,639

5 Sheets-Sheet 2 FIG. 2

Patented March 21, 1972v 5 Sheets-Sheet 5 Patented March 21, 1972 5Sheets-Sheet 5 //8 Hg. 6 A) F/G. 6 M) Hg. 6 K

AIR PUMPS This invention relates in general to air pumps and inparticular to new and improved air cooled vacuum pumps and compressors.

A common type of pump for pumping a compressible gas such as air to acaptive system is a diaphragm and piston pump. In this type of pump, areciprocating diaphragm and piston positively displace the gas from acylinder'during the discharge stroke of the piston. Normally, thesepumps are of small capacity and are generally single acting and aircooled. The diaphragms and pistons are usually moved reciprocatingly bya cam, crankshaft and cam follower connecting rod mechanism, or theequivalent, deriving motion from a driving source such as an electricmotor. On being compressed, the gas is expelled through valves whichopen readily upon slight differential pressures. The term air pump isused generically hereinafter to describe these and other gascompressors, vacuum pumps, and the like.

The compression of a gas, such as air into a smaller volume gives riseto problems in designing such pumps. For example, a major problem in thedesign of air pumps is the need to remove the heat of compression fromthe pumping element. Disposal of this heat of compression generatedduring the compression cycle has always been a problem effecting thereliability, longevity and efficiency of air pumps. This heat disposalproblem is especially severe in pumps or compressors of the flexiblediaphragm type since the heat generated causes excessive embrittlementof the diaphragm and, consequently, a substantially reduced cycle lifethereof.

Heretofore, air-cooled fluid pumps have employed heatradiating fins castintegral with the pump body to furnish additional radiating surface tocarry off the heat of compression. The use of these cooling fins hasbeen successful only to a degree in providing a solution to the heatdisposal problem. For example, these fins have not provided sufficientcooling of the units to adequately extend the cycle life of thediaphragms in the pumps. Consequently, the diaphragms have worn out tooquickly resulting in costly maintenance problems and substantiallyreduced efficiency of the pump unit.

An additional long standing problem in designing air pumps, andparticularly air compressors is the reduction of noise level caused bythe valve operation during compression of the gas. No completelyadequate and economical solution has been suggested heretofore to reducethe air borne noise level caused by the compression and discharge of gasin an air compressor unit. Therefore, it would-be advantageous toprovide air compressors having means for muffling or dampening thisworking noise.

Accordingly, an object of the present invention is to provide new andimproved air pumps. In particular, an object is to provide air cooledvacuum pumps and compressors which overcome the problem of disposal ofthe heat of compression.

A related object is to provide air cooled air pumps of the diaphragmtype which are more efficient in operation, require less time consumingand costly maintenance and wherein the diaphragm component thereof has asubstantially extended cycle life.

Another object is to provide air compressors which are substantiallyquieter in operation. More specifically, an object is to provide aircompressors having noise dampening or muffler means to reduce the airborne noise level of the unit.

In accordance with one embodiment of the invention, a motor operated,air cooled pump is provided having a movable pump member comprising apiston and diaphragm assembly. The pump member is arranged to move in anundulating reciprocal motion within a pumping chamber to producecompressed air. Ducts are provided to allow cool air to enter the pumpbody and cool the pumping chamber. After cooling the pumping chamberand, correspondingly, the piston and diaphragm therein, this air isdrawn, by a fan operatively connected to the motor, through channels inthe pump body over the motor, thus providing a cooling effect for themotor. The air is then expelled from the pump through outlet ventsprovided in the pump body. This arrangement promotes more efficient andeffective cooling of the entire pump unit and, particularly, of thepumping chamber, piston and diaphragm resulting in higher compressionefficiency, lower discharge air temperature and longer diaphragm life.

The abovementioned and other features and objects of this invention andthe manner of obtaining them will become more apparent, and theinvention will be best understood by reference to the followingdescription of embodiments of the invention taken in conjunction withthe accompanying drawings in which:

FIG. 1 is a pictorial representation of the inventive air pump in theform of an air compressor;

FIG. 2 is a cross-sectional side view of the air compressor taken alongline 2 2 of FIG. 1;

FIG. 3 is a sectional view of the piston and connector rod assembly inthe air compressor of FIG. 1 showing the cavity in the body of thepiston with the cellular material therein;

FIG. 4 is a schematic stop action representation showing the operationof the air compressor of FIG. 1 during the suction stroke and dischargestroke of the pumping member;

FIG. 5 is a sectional view of a vacuum pump head assembly replacing theair compressor cylinder head assembly shown in the encircled area 5 ofFIG. 3; and

FIG. 6 is a schematic stop action representation showing the operationof a vacuum pump, employing the vacuum pump head assembly of FIG. 5,during the suction stroke and discharge stroke of the pumping member.

In the FIG. 1 pictorial representation of a preferred embodiment of theinvention, an air compressor assembly 10 is shown. The assembly includesa housing or casing 12, a front cover plate 14, a rear rotor housing 16and a cylinder head 18. These constituent parts are securably fastenedtogether to form the assembly 10 by any suitable arrangement such asscrews, bolts and the like. The assembly 10 of the present embodiment isconstructed for use as a portable unit. A mounting position 20 isprovided for an adjustable handle (not shown) so that the assembly 10can be easily transported. However, the assembly 10 can also be mountedin a stationary positioned, if desired. Fins 21 are provided about theouter surface of the assembly 10.

Means are provided for cooling a cylinder or pumping chamber 22 in thehousing 12 by providing a flow of cool air about the outer surfacethereof whereby the heat of compression generated within the cylinder 22is effectively and efficiently dissipated. More specifically, aplurality of ducts or ports, such as duct 24, are positioned about thesurface of the head 18 to provide inlets for entry of cool air into thehousing 12. The ducts 24 in head 18 communicate with channels orpassageways 26 in housing 12 and form continuous paths with thesechannels or passageways 26. Thus, as shown generally by arrows a, b andc in FIG. 1, air flows into the assembly 10 through ducts 24. The coolair then circulates about the outer surface of the cylinder 22 in thehousing 12 through the channels or passageways 26. Corresponding pathsare further provided through the fan scroll cavity 17 in the motor endcover plate 16 so that a continuous flow path is provided from the inletducts 24 through the entire pump body including housing 12 and rotorhousing 16 to outlet vents 28.

Means are further provided for cooling a motor 30 in the assembly 10 bythe passage of cooling air thereover. More particularly, additional coolair inlet ports 32 are provided through the base of the housing 12.These ports 32 connect with channels 26 in the housing 12. The airentering these ports 32 combines with the air flowing in channels 26which entered through ducts 24. This combined air flow enhances coolingof the motor bearings and windings of the motor 30 as the air passesover the motor 30 and through the motor end cover plate 16 before beingexpelled through outlet vents 28. This cooling of the motor 30 and themotor bearings promotes extended bearing life and substantiallyincreases the motor ef-.

ficiency.

Means, such as fan 34 best seen in FIG. 2, positioned in the motor endcover plate 16 adjacent to outlet vents 28 are employed to achieve thedesired air flow into and through the assembly 10. In greater detail,the fan 34 is operatively connected to the motor 30 and acts to draw airinto the assembly through ducts 24 and ports 32 and causes this air tocirculate through the channels or passageways 26 provided in theassembly 10. Additionally, the fan 34 forces the air out of the assembly10 through outlet vents 28 after the air has completed its flow paththrough the pump body.

As best illustrated in FIG. 2, it is seen that the air compressor 10 isoperated by a motor 30 such as an electrically driven motor mounted in aspace provided in the housing 12 and motor end cover plate 16. The motor30 is operatively attached to the fan 34 in the motor end cover plate 16by a shaft 36 and bearings 38.

A shaft 40 extends from the opposite end of the motor 30 and isconnected to a connecting rod assembly 42 which extends in a verticalplane perpendicular to the axis of the shaft 40. This connection is madein any suitable manner such as by bearings 43 and 44 and a cam oreccentric 46 to impart motion to the rod 42. The motion thus attainedcan be characterized generally as reciprocal motion in a plane parallelto the axis of the shaft 40 and as a slight rocking or undulating motionin a plane perpendicular to this axis.

The upper end of the rod 42 is flared outwardly to form a piston-likemember 48 which is disposed within a pump cylinder or chamber 50 in thehousing 12. A cavity or chamber 52 defined by shell 54 is providedwithin the piston body 48 as shown in FIG. 3. The cavity 52 is open atthe top and is covered by a cover plate 56. The cover plate 56 isattached to piston 48 by cover plate screws 55. An outlet opening orport 57 is provided in cover plate 56 and is positioned to correspondwith the central area of cavity 52. The port 57 is enclosed at its upperend by a suitable valve mechanism 58, such as a feather valve, a reedvalve and the like. Holes 60 are provided through the base of the shell54 to allow air to enter therein.

Means such as cellular material 62 are provided for reducing the noisecaused by the operation of the valves during the compression and exhaustcycles of the compressor 10. More specifically, the cavity 52 contains acellular material or substance 62 which has a characteristic property, ahigh loss of energy due to its internal working responsive to mechanicalvibrations. Exemplary of suitable cellular materials having theseproperties are certain soft plastics, elastomers, cellulose, expandedrubber and the like. In operation, air enters cavity 52 through holes 60and then passes through the cellular material 62 having the highinternal loss properties before it is expelled from the cavity 52through outlet opening 57 and valve 58. Consequently, the sound wavesare damped or muffled to a high degree due to the acoustical impedanceby the cellular material 62 having inefficient vibration transmissioncharacteristics. This dampening or muffiing effect on the sound wavesresults in substantially reduced air borne noise level and, thus,quieter valve operation. Accordingly, the cavity 52 with material 62forms a noise dampening chamber or muffler which reduces the air bornevalve noise and thus provides a quieter operating pump.

An annular shaped flexible diaphragm 64, of suitable elastic materialsuch as rubber, is secured to the upper face of the piston 48 by thecover plate or retainer 56 and screws 55. The outer periphery of thediaphragm 64 is clamped in sealing engagement between the outer end ofthe cylinder 50 and the cylinder head 18. The cylinder head 18 is boltedto the outer end of the cylinder 50.

The cylinder head 18 includes an inverted cuplike body 68 closed on theinner end by an exhaust or valve plate 70. A compression chamber 72 isthus formed between the cover plate 56 and the exhaust plate 70. Acentral outlet opening or port 74 extends through exhaust plate 70 andterminates in communication with the compression chamber 72. The outletopening 74 is enclosed at the top by a suitable valve mechanism 76 suchas a feather valve, a reed valve and the like to interconnect chamber 72with a high pressure chamber 78. A discharge port 80 interconnects thehigh pressure chamber 78 to a suitable outlet conduit 82 for transfer ofthe compressed air directly to a compressed air load.

The front cover plate 14 is provided with an inlet port 84 to allow airto enter the compressor assembly 10. The port 84 is abutted by aremovable filter material 85 such as porous felt and the like. Theperforated metal plate 86 retains filter material 85. This filtermaterial 85 filters the air entering the unit through port 84 toeliminate any undesirable contaminants before the air enters the cavity52 of the piston 48 through the holes 60 in the shell 54 and,subsequently, the compression chamber 72.

The operation of the compressor 10 is depicted in the schematic stopaction illustrations, FIGS. 4(a), 4(b), 4(c), and 4(d). During thesuction stroke (FIG. 4a) of the piston 48 when the piston 48 anddiaphragm 64 move downwardly, air from filter 85 enters the housing 12and is drawn into cavity 52 through holes 60. The air then passesthrough cellular material 62. The valve 58 is open due to thedifferential pressure between cavity 52 and compression chamber 72. Thisallows air to flow through outlet port 57 and into compression chamber72.

As the downward suction stroke ends and the discharge or exhaust strokebegins, the piston 48 and diaphragm 64 reverse direction and begin totravel upward. At some point in this upward discharge stroke (FIG. 4b),the pressure in the cavity 52 and the pressure in the compressionchamber 72 approximately equalize and the valve 58 closes. The air inthe compression chamber 72 is thus trapped therein. The air cannotescape into the cavity 52 since valve 58 is closed; nor can the air passinto the high pressure chamber 78 since the differential pressurebetween the compression chamber 72 and the high pressure chamber 78 issuch that valve 76 is closed.

The piston 48 continues its upward discharge stroke (FIG. 40) and thepressure of the air trapped in the compression chamber 72 increases dueto the compressive action of piston 48 thereon. The pressure of the airin chamber 72 continues to mount until a point is reached at which thepressure differential between the compression chamber 72 and the highpressure chamber 78 is such that the valve 76 opens. Then the compressedair passes through outlet opening 74 from the compression chamber 72into the high pressure chamber 78 and hence through discharge port 80into the outlet conduit 82.

Subsequently, the piston 48 begins its downward suction stroke again. Atsome point in this downward suction stroke (FIG. 4d), the pressuredifferential between the high pressure chamber 78 and the compressionchamber 72 becomes such that valve 76 closes thus returning the unit toits approximate starting condition wherein valves 58 and 76 are closed.Thereafter, as the compressor continues to operate, the above describedoperation is repeated continuously.

In a further embodiment of the present invention, the inventive airpumps are vacuum pumps. The structure and operation of the vacuum pumpsgenerally is similar to that heretofore described with reference to aircompressors in FIGS. 1-4. The housing 12, the front cover plate 14 andthe rear rotor housing 16 and the constituent elements therein are thesame as above described. However, the encircled area 5 in FIG. 2comprising cylinder head 18 of compressor 10 is replaced by a vacuumpump head 88 shown in FIG. 5.

The vacuum pump head 88 includes an inverted cuplike body 90 with acentrally positioned ridge 92. The body 90 is closed on the inner end bya valve plate 94. In assembly, the bottom end of ridge 92 is sealed withplate 94 forming two discrete chambers 96 and 98 in body 90. Chamber 96is an inlet chamber and chamber 98 is a discharge chamber.

A compression chamber similar to chamber 72 of compressor 10 is formedbetween the valve plate 94 and a cover plate such as cover plate 56 inhousing 12 shown in FIGS. 23. An inlet opening or port 100 and anexhaust opening or port 102 are provided in plate 94. The inlet opening100 interconnects inlet chamber 96 with compression chamber 72 and,likewise, exhaust opening 102 interconnects compression chamber 72 withdischarge chamber 98. Inlet opening 100 is enclosed at the bottom withinchamber 72 by a suitable valve mechanism 104 and exhaust opening 102 isenclosed at the top within discharge chamber 98 by a similar type valvemechanism 106. Suitable valve mechanisms 104 and 106 include feathervalves, reed valves and the like. The valves 104 and 106 are held inposition by valve screws 108 and valve keepers 1 10.

An inlet port 112 interconnects a suitable inlet conduit 1 14 to theinlet chamber 96 for introduction of air into the head 88. This airsubsequently passes through opening 100 in plate 94 into compressionchamber 72. After compression, the compressed air is expelled from thepump head 88 through opening 102 in plate 94 and discharge chamber 98into a discharge port 116. The discharge port 116 interconnects thedischargechamber 98 to a suitable outlet conduit 1 l8 and the compressedair is thereby transferred directly to a compressed air load.

The operation of the vacuum pump is depicted in the schematic stopaction illustrations, FIGS. 6(a), 6(b), 6(0), and 6(d). During thesuction stroke (FIG. 6a) of the piston 48, when the piston 48 anddiaphragm 64 move downwardly, air from inlet conduit 114 enters inletchamber 96 through inlet port 112. The valve 104 enclosing opening 100in valve plate 94 opens due to the differential pressure between inletchamber 96 and compression chamber 72. This allows the air to flow intocompression chamber 72.

As the downward suction stroke ends and the discharge or exhaust strokebegins, the piston 48 and diaphragm reverse direction and begin totravel upward. At some point in this upward discharge stroke (FIG. 6b),the pressure in the inlet chamber 96 and the pressure in the compressionchamber 72 approximately equalize and valve 104 closes. The air in thecompression chamber 72 is thus trapped therein. The air cannot escapeinto the inlet chamber 96 since valve 104 is closed; nor can the airpass into the discharge chamber 98 since the differential pressurebetween the compression chamber 72 and the discharge chamber 98 is suchthat valve 106 is closed.

The piston 48 continues its upward discharge stroke (FIG. 60) and thepressure of the air trapped in the compression chamber 72 increases dueto the compressive action of piston 48 thereon. The pressure of the airin chamber 72 continues to mount until a point is reached at which thepressure differential between the compression chamber 72 and thedischarge chamber 98 is such that the valve 106 opens. Then thecompressed air passes through exhaust opening 102 from the compressionchamber 72 into the discharge chamber 98 and hence through dischargeport 116 into outlet conduit 118.

Subsequently, the piston 48 begins its downward suction stroke again. Atsome point in this downward suction stroke (FIG. 6d), the pressuredifferential between the discharge chamber 98 and the compressionchamber 72 becomes such that valve 106 closes thus returning the unit toits approximate starting condition wherein valves 104 and 106 areclosed.

Thereafter, as the vacuum pump continues to operate, the above describedoperation is repeated continuously.

From the above description, it should now be clear that air pumps havebeen provided which effectively and efficiently dispose of the heat ofcompression generated by the compression of gases in the pump. Thisdisposal of heat or cooling feature of the invention is highlyadvantageous in promoting higher compression efficiency of the pumps,lower discharge air temperature and longer diaphragm life. Additionally,the unique and superior cooling feature of the inventive pumps providesexcellent cooling of the motor and motor bearings and windings whichpromotes increased motor life and materially increases motor efficiency.A further advantageous feature of the present invention is the provisionof a muffler or damper means resulting in quieter operating pumps.

While the principles of the invention have been described above inconnection with specific apparatus and applications, it is to beunderstood that t 15 descr ption 15 made only by way of example and notas a limitation on the scope of the invention.

We claim:

1. A motor operated air cooled pump including a pump body havingdisposed therein a pumping chamber, said pumping chamber having amovable pump member disposed therein, said pump member operating with asuction stroke to draw air from a first air inlet means through a firstair duct channel means into said pumping chamber and a discharge stroketo compress said air and to expel the compressed air from said pumpchamber through a first air outlet means, second air inlet and outletmeans separate from said first air inlet and outlet means, said secondair inlet and outlet means being positioned about the surface of saidpump body, said second air inlet means being connected to said secondair outlet means by second air duct channel means separate from saidfirst air duct channel means, said second air duct channel meansextending through said pump body in a manner such that said secondchannel means extend in sequence from said second air inlet means aroundthe outer surface of said pumping chamber over the surface of said motorand then to said second air outlet means, means for drawing cool airinto said pump body through said second air inlet means and for drawingsaid air through said second channel means and for expelling said airfrom said pump body through said second air outlet means, said aircirculating through said second channel means in said pump body firstproviding cooling of said pumping chamber and said pump member disposedtherein whereby heat of compression generated by said suction anddischarge strokes of said pump member is removed and then cooling themotor bearings and windings of said motor as said air is drawn over saidmotor surface.

2. The air cooled pump of claim 1 wherein said pump member comprises apiston and diaphragm assembly.

3. .The air cooled pump of claim 2 wherein said pump is an aircompressor.

4. The air cooled pump of claim 2 wherein said pump is a vacuum pump.

1. A motor operated air cooled pump including a pump body having disposed therein a pumping chamber, said pumping chamber having a movable pump member disposed therein, said pump member operating with a suction stroke to draw air from a first air inlet means through a first air duct channel means into said pumping chamber and a discharge stroke to compress said air and to expel the compressed air from said pump chamber through a first air outlet means, second air inlet and outlet means separate from said first air inlet and outlet means, said second air inlet and outlet means being positioned about the surface of said pump body, said second air inlet means being connected to said second air outlet means by second air duct channel means separate from said first air duct channel means, said second air duct channel means extending through said pump body in a manner such that said second channel means extend in sequence from said second air inlet means around the outer surface of said pumping chamber over the surface of said motor and then to said second air outlet means, means for drawing cool air into said pump body through said second air inlet means and for drawing said air through said second channel means and for expelling said air from said pump body through said second air outlet means, said air circulating through said second channel means in said pump body first providing cooling of said pumping chamber and said pump member disposed therein whereby heat of compression generated by said suction and discharge strokes of said pump member is removed and then cooling the motor bearings and windings of said motor as said air is drawn over Said motor surface.
 2. The air cooled pump of claim 1 wherein said pump member comprises a piston and diaphragm assembly.
 3. The air cooled pump of claim 2 wherein said pump is an air compressor.
 4. The air cooled pump of claim 2 wherein said pump is a vacuum pump. 